This invention relates to a packaging unit containing two different compositions to be mixed together before use, which includes a cap having a chamber for holding one composition, a container holding another composition, and a membrane separating the two compositions, where the cap is configured to facilitate breaking or piercing the membrane to allow the two compositions to mix.
Biphase products are those in which the product is supplied as two separate components, frequently a liquid and a powder but also liquid-liquid and paste-paste combinations, in packaging which allows the components to be kept separate until the time of use The need to keep the components separate arises for a number of reasons, but usually because their interaction would reduce the quality of one or the other, or because some interaction essential to product functioning occurs over a short timeframe and must not be initiated prematurely.
There are many designs of packaging which perform the function of keeping the components separate, yet permits their mixing within the pack. For example, one compartment of the packaging is configured as a chamber within the cap of a container, and it may also incorporate some form of applicator or dispense feature.
Common means by which the components are combined within the packaging are by the breaking of a frangible membrane or peelable seal. Of the designs in commercial use, many are activated by the consumer pressing a button, which in turn breaks the frangible membrane. In other examples, its pressing causes orifices between the chambers of the packaging to be aligned. The button is generally configured as a piston operating within a barrel.
The packaging should keep the components of the two chambers not only physically separate, but also prevent any volatile components from permeating through the membrane or seal into the other compartment. Also, the components may need protection from the atmosphere external to the packaging. It follows that the interference fit between the button, and the barrel, and the nature of the interface between the chambers should be as secure as possible. One consequence of this is that the force needed to depress the button is often higher than acceptable to the target user group for the product This can be exacerbated by product causing friction between the parts.
In some designs using aluminum foil as a frangible membrane, the product chamber within the cap is configured as a conventional blister, particularly if the component to be contained within is a tablet. However, such designs require the additional step of blister packing prior to inserting the blister into the cap, use a greater number of different materials, and the blister is without features to cause its collapse. In some of these the foil face of the blister is used to seal to the rim of the container that comprises the second chamber. Being a hard surface and lacking a resilient design feature this seat may not fully accommodate variations in the container rim or backing-off of the application torque, and prove insecure.
In several designs of such packaging, the button is associated with a screw thread, such that the mechanical advantage of the screwing action substantially reduces the effort required of the user. The action of joining the compartments is most frequently that a cap is further tightened, or only partially unscrewed, prior to full opening. Such action, and the pause whilst the components of the product mix together, is counterintuitive for many users, and misuse may result in reduced product performance.
Moreover, the means of filling the product components into the packaging should be considered. It is generally preferable to avoid multiple steps in the filling and assembly of the cap components at the site of product manufacture, or that filling and assembly at a different location with specialist equipment is necessary. In commercial units, the product chamber within the cap is frequently a simple two piece construction in which one piece is filled and the other is pressed on to it, in the manner of filling a small container. This sub-assembly is also fitted to the body of the main container in a conventional manner.
The complexity of supply of packaging components, and their ultimate disposal, should also be considered. It is always preferable to reduce the number of components and materials used.
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